Enteric therapy of patients involves administering fluid nutrients and various medical preparations through a flexible feeding tube into the gastrointestinal tract. Such feeding tubes are inserted either nasally, surgically, percutaneously, or orally, and, therefore, must be of a small cross sectional diameter. Nasogastrointestinal tubes are inserted into a patient's nostril, guided through the nasopharynx and oropharynx into the esophagus. The tube then advances into the patient's stomach or duodenum either by peristaltic movement or by the use of an internal guide or stylet.
Typically, enteral feeding is utilized when patients are unable to swallow or are having difficulty masticating or otherwise are unable to achieve adequate nutritional intake. By using an enteral feeding tube to supply nutrient fluids to patients, the risks of intravenous hyperalimentation, viz., sepsis or metabolic derangement, are avoided.
Various types of feeding tubes have been utilized for the enteric therapy of patients. For example, U.S. Pat. No. 1,899,781 issued Feb. 28, 1933 to J. R. Twiss, describes a stomach tube having a hollow metal bucket forming the tube outlet. The bucket exhibits a concave formation with the intermediate portion of the bucket having a considerably reduced diameter with respect to the end portions or shoulders. A ball weight is attached to the distal end of the bucket and tube, and serves to anchor the tube in the patient's stomach. This feeding tube, however, may cause patient discomfort during intubation. In addition, due to the shape and small openings of the bucket, this tube is more susceptible to clogging by coagulated matter.
Another feeding tube, described in U.S. Pat. No. 4,516,970 issued May 14, 1985 to Kaufman et al., contains staggered apertures in the walls of the distal end of the tube. These apertures permit the flow of fluids from the tube; however, they also serve to weaken the tube wall, resulting in a greater likelihood of the wall collapsing, twisting or bending. Any of these conditions would cause interference with the flow of fluids into and out of the tube and could also cause difficulties with the progression of the tube during intubation.
U.S. Pat. No. 4,351,342 issued Sept. 28, 1982 to Wiita et al., describes a tube having an enlarged tip at its distal end. This enlarged tip may cause pain to a patient during intubation and may permit the accumulation of fluids, resulting in coagulation and clogging of the tube.
To provide for easier intubation, Quinn et al., in U.S. Pat. No. 4,490,143 issued Dec. 25, 1984, describe a flexible feeding tube having an internally weighted guide tip at its distal end. The feeding tube has a bead-like bolus located proximal to the guide tip. The bolus contains lateral apertures which permit the flow of fluids to and from the tube. More specifically, the bolus is partially hollow and contains a cylindrical channel which is perpendicular to the tube lumen. At least two openings are formed at the ends of the cylindrical channel, thereby permitting the passage of fluids. In addition, the bolus provides a rigid housing for the distal end of a stylet during intubation. Although this feeding tube assembly provides for somewhat easier intubation, the relatively small openings in the bolus are very susceptible to fluid flow restriction and clogging.
On attempt to deal with these problems was disclosed in U.S. Pat. No. 4,594,074 issued June 10, 1986 to Andersen et al. Andersen et al. utilize an enteral feeding tube having a tubular shaped, non-collapsible bolus on the distal end of the tube. This bolus has at least one outlet opening for fluid communication through its side wall. The side walls of the bolus are upright and vertical, reducing the likelihood of the tube bolus collapsing. To maximize fluid flow and minimize occlusion, the side walls of the bolus opening are recessed to provide for a larger outlet. The passage of the bolus contains an upwardly inclining floor to regulate the stream of fluids from the tube.
One problem encountered in all the above prior art enteral feeding tubes is the difficulty of intubation when moderate restrictions are encountered. For example, a tube bolus must be forced past a tissue growth or tumor to achieve placement in a patient's stomach. This situation may cause great discomfort and pain to a patient.
Another problem encountered with prior art tubes is the occlusion of the tube outlet with gastrointestinal debris or coagulated matter. The outlets of prior art tubes may also become blocked during aspiration by being drawn up against the mucosal lining of the gastrointestinal tract.
As recognized by those in the industry, the most preferred design of an enteral feeding tube to achieve a maximum rate of fluid flow out of the tube, would be an open-ended tube. Such a tube, however, would be susceptible to occlusion, especially during aspiration, and could easily become caught against the mucosal lining making intubation difficult. Accordingly, an elongated guide tip or distal end weighted tip would be desirable in conjunction with an open-ended tube. These end tips aid intubation and minimize trauma to the mucosal linings of the gastrointestinal tract.
Hence, prior to the development of the present invention, a need existed for an interal feeding tube which could be inserted with minimal discomfort or risk to the patient and would not become occluded with fluid nutrients, medical preparations, or mucous.